C++

Forum

 
Help me to understand this warning

SitiMustaqim (4)
Hi All,
I am very new to C. In case I would like to compile a mex based c file taken from a website; using MATLAB. I encountered this warning:


chinterpol2D.c
batchinterpol2D.c(113) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(147) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(180) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(214) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(314) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(348) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(381) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(416) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for example, in one function
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
extern void BatchInterpolatedGradX2DMirr (
float *Bout,
float *Bcoeff,
long Width,
long Height,
double nx,
double offx,
double mx,
double ny,
double offy,
double my,
long SplineDegree
)
{ /* begin BatchInterpolatedGradX2DMirr */

double x, y;
long idx;
long idcoordx, idcoordy;

idx = 0;
for (idcoordy = 0; idcoordy < ny; idcoordy++) {
for (idcoordx = 0; idcoordx < nx; idcoordx++) {

x = (float)(idcoordx - offx) / mx;
y = (float)(idcoordy - offy) / my;

Bout[idx++] =(float) InterpolatedGradXMirr(Bcoeff,
Width, Height, x, y, SplineDegree)/mx;
}
}
} /* end BatchInterpolatedGradX2DMirr */

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
I add (float) to correct them but still fail.

Please advise me. I am looking for help.

Thank you so much.

Fransje (435)
You could try this: 
1
2
 
Bout[idx++] = static_cast < float > ( InterpolatedGradXMirr(Bcoeff, 
Width, Height, x, y, SplineDegree)/mx );


Have a look here: http://cplusplus.com/doc/tutorial/typecasting/

Good luck!
TheIdeasMan (6817)
Why use floats at all? make all the floats doubles - no need for the cast. Or just remove the cast to float as x & y are doubles anyway.

HTH

Please use code tags - the <> button on the right.
Last edited on
SitiMustaqim (4)
Hi, Thank you all for the reply. I will try.
SitiMustaqim (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
 
/*******************************************************************************

        Batch interpolation for each location of points (+ deformation)
        using point interpolation functions with mirror and zero end condition

        Created by Se Young Chun, Sep 30, 2006, the University of Michigan

*******************************************************************************/

#include	<math.h>
#include	<stddef.h>
#include	<stdio.h>
#include	<stdlib.h>

#include	"batchinterpol2D.h"
#include	"interpol2D.h"
 
extern void     BatchInterpolatedValue2DMirr (
                        float   *Bout, 
                        float   *Bcoeff, 
                        long    Width,   
                        long    Height,   
                        double  nx,       
                        double  offx,    
                        double  mx,      
                        double  ny,     
                        double  offy,   
                        double  my,      
                        long    SplineDegree  
		)
{ /* begin BatchInterpolatedValue2DMirr */

	double	x, y;
	long	idx;
	long	idcoordx, idcoordy;

	idx = 0;	
	for (idcoordy = 0; idcoordy < ny; idcoordy++) {
		for (idcoordx = 0; idcoordx < nx; idcoordx++) {
			
			x = (idcoordx - offx) / mx;
			y = (idcoordy - offy) / my;

			 Bout[idx++] = InterpolatedValueMirr(Bcoeff, 
					Width, Height, x, y, SplineDegree);
		}
	}
} /* end BatchInterpolatedValue2DMirr */


extern void     BatchInterpolatedValue2DMirrWarp (
                        float   *Bout,   
                        float   *Bcoeff, 
                        long    Width, 
                        long    Height,
                        double  nx,      
                        double  offx,  
                        double  mx,    
                        float   *WarpX,
                        double  ny,     
                        double  offy,   
                        double  my,      
                        float   *WarpY,   
                        long    SplineDegree 
                )
{ /* begin BatchInterpolatedValue2DMirrWarp */

        double  x, y;
        long    idx;
        long    idcoordx, idcoordy;

        idx = 0;
        for (idcoordy = 0; idcoordy < ny; idcoordy++) {
                for (idcoordx = 0; idcoordx < nx; idcoordx++) {

                        x = (idcoordx + WarpX[idx] - offx) / mx;
                        y = (idcoordy + WarpY[idx] - offy) / my;

                        Bout[idx++] =  InterpolatedValueMirr(Bcoeff,
                                        Width, Height, x, y, SplineDegree);
                }
        }
} /* end BatchInterpolatedValue2DMirrWarp */


extern void     BatchInterpolatedGradX2DMirr (
                        float   *Bout, 
                        float   *Bcoeff,  
                        long    Width,    
                        long    Height,  
                        double  nx,     
                        double  offx,  
                        double  mx,   
                        double  ny,  
                        double  offy, 
                        double  my,   
                        long    SplineDegree
		)
{ /* begin BatchInterpolatedGradX2DMirr */

	double	x, y;
	long	idx;
	long	idcoordx, idcoordy;

	idx = 0;	
	for (idcoordy = 0; idcoordy < ny; idcoordy++) {
		for (idcoordx = 0; idcoordx < nx; idcoordx++) {
			
			x = (idcoordx - offx) / mx;
			y = (idcoordy - offy) / my;

			Bout[idx++] =  InterpolatedGradXMirr(Bcoeff, 
					Width, Height, x, y, SplineDegree)/mx;
		}
	}
} /* end BatchInterpolatedGradX2DMirr */

extern void     BatchInterpolatedGradX2DMirrWarp (
                        float   *Bout,  
                        float   *Bcoeff,
                        long    Width,  
                        long    Height, 
                        double  nx,     
                        double  offx,   
                        double  mx,     
                        float   *WarpX, 
                        double  ny,     
                        double  offy,   
                        double  my,     
                        float   *WarpY, 
                        long    SplineDegree
                )
{ /* begin BatchInterpolatedGradX2DMirrWarp */

        double  x, y;
        long    idx;
        long    idcoordx, idcoordy;

        idx = 0;
        for (idcoordy = 0; idcoordy < ny; idcoordy++) {
                for (idcoordx = 0; idcoordx < nx; idcoordx++) {

                        x =  (idcoordx + WarpX[idx] - offx) / mx;
                        y =  (idcoordy + WarpY[idx] - offy) / my;

                        Bout[idx++] = InterpolatedGradXMirr(Bcoeff,
                                        Width, Height, x, y, SplineDegree)/mx;
                }
        }
} /* end BatchInterpolatedGradX2DMirrWarp */


extern void     BatchInterpolatedGradY2DMirr (
                        float   *Bout,  
                        float   *Bcoeff,
                        long    Width,  
                        long    Height, 
                        double  nx,     
                        double  offx,   
                        double  mx,     
                        double  ny,     
                        double  offy,   
                        double  my,     
                        long    SplineDegree 
                )
{ /* begin BatchInterpolatedGradY2DMirr */

	double	x, y;
	long	idx;
	long	idcoordx, idcoordy;

	idx = 0;	
	for (idcoordy = 0; idcoordy < ny; idcoordy++) {
		for (idcoordx = 0; idcoordx < nx; idcoordx++) {
			
			x = (idcoordx - offx) / mx;
			y = (idcoordy - offy) / my;

			Bout[idx++] = InterpolatedGradYMirr(Bcoeff, 
					Width, Height, x, y, SplineDegree)/my;
		}
	}
} /* end BatchInterpolatedGradY2DMirr */

extern void     BatchInterpolatedGradY2DMirrWarp (
                        float   *Bout,
                        float   *Bcoeff, 
                        long    Width,   
                        long    Height, 
                        double  nx,    
                        double  offx, 
                        double  mx,  
                        float   *WarpX, 
                        double  ny,    
                        double  offy, 
                        double  my,  
                        float   *WarpY, 
                        long    SplineDegree 
                )
{ /* begin BatchInterpolatedGradY2DMirrWarp */

        double  x, y;
        long    idx;
        long    idcoordx, idcoordy;

        idx = 0;
        for (idcoordy = 0; idcoordy < ny; idcoordy++) {
                for (idcoordx = 0; idcoordx < nx; idcoordx++) {

                        x = (idcoordx + WarpX[idx] - offx) / mx;
                        y = (idcoordy + WarpY[idx] - offy) / my;

                        Bout[idx++] = InterpolatedGradYMirr(Bcoeff,
                                        Width, Height, x, y, SplineDegree)/my;
                }
        }
} /* end BatchInterpolatedGradY2DMirrWarp */

extern void     BatchInterpolatedValue2DZero (
                        float   *Bout, 
                        float   *Bcoeff, 
                        long    Width,   
                        long    Height,   
                        double  nx,       
                        double  offx,    
                        double  mx,      
                        double  ny,     
                        double  offy,   
                        double  my,      
                        long    SplineDegree  
		)
{ /* begin BatchInterpolatedValue2DZero */

	double	x, y;
	long	idx;
	long	idcoordx, idcoordy;

	idx = 0;	
	for (idcoordy = 0; idcoordy < ny; idcoordy++) {
		for (idcoordx = 0; idcoordx < nx; idcoordx++) {
			
			x = (idcoordx - offx) / mx;
			y = (idcoordy - offy) / my;

			Bout[idx++] = InterpolatedValueZero(Bcoeff, 
					Width, Height, x, y, SplineDegree);
		}
	}
} /* end BatchInterpolatedValue2DZero */



SitiMustaqim (4)
WARNINGS

batchinterpol2D.c
batchinterpol2D.c(45) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(80) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(113) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(147) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(180) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(214) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(246) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(281) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(314) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(352) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(385) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
batchinterpol2D.c(420) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data
Lowest0ne (1536)
batchinterpol2D.c(45) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of data


In file batchinterpol2D.c @ line 45 the '=' has triggered warning C4244, which is a conversion from double to float warning. Edit line 45 so that you don't do that by making both data types floats or doubles.
TheIdeasMan (6817)
As i said earlier, get rid of the floats - the ones you have Bout & Bcoeff - make all occurrences of them doubles.
Topic archived. No new replies allowed.