Hi! I’m trying to replicate, in Matlab, compiled algorithms implemented in C using single-precision arithmetic; I have the C source code, and an executable which is reputed to implement said C source, but no convenient means to compile and link said source myself. (Yes, I know I can download the Microsoft C compiler, incl. a no-frills version of Visual Studio, for free, but that’s hardly "convenient.") I’ve implemented the algorithms and I’m 99% sure they’re right because the "residuals" (the difference between my results and those of the original C implementations) are more-or-less randomly distributed around zero, and about 85% of them are within half of the precision of the C implementations’ output (which varies, but, for example, when it’s 1e-4, 85% of my residuals satisfy abs(res)<5e-5). It’s the other 15% that leave me 1% uncertain, and my attempts to explain the discrepancy have brought me to the single/double precision issue: I have good cause to suspect that the C implementations are using single-precision arithmetic, and I’ve been led to believe that Matlab always performs double-precision arithmetic, even on single precision "data," yes? (I tried making ‘single’ all the data in my implementation, and confirmed after each "gross" calculation that the output remained so, but that only reduced the number of bad residuals by 3 out of 4118 total input points.) So, I’m wondering if there’s either a "convenient" way to simulate single-precision arithmetic in Matlab (I searched File Exchange for relevant functions, but found none) or to estimate/bound the "error" introduced by using single-precision arithmetic (including power/root and exponential/log functions) instead of double. Thanks!Hi! I’m trying to replicate, in Matlab, compiled algorithms implemented in C using single-precision arithmetic; I have the C source code, and an executable which is reputed to implement said C source, but no convenient means to compile and link said source myself. (Yes, I know I can download the Microsoft C compiler, incl. a no-frills version of Visual Studio, for free, but that’s hardly "convenient.") I’ve implemented the algorithms and I’m 99% sure they’re right because the "residuals" (the difference between my results and those of the original C implementations) are more-or-less randomly distributed around zero, and about 85% of them are within half of the precision of the C implementations’ output (which varies, but, for example, when it’s 1e-4, 85% of my residuals satisfy abs(res)<5e-5). It’s the other 15% that leave me 1% uncertain, and my attempts to explain the discrepancy have brought me to the single/double precision issue: I have good cause to suspect that the C implementations are using single-precision arithmetic, and I’ve been led to believe that Matlab always performs double-precision arithmetic, even on single precision "data," yes? (I tried making ‘single’ all the data in my implementation, and confirmed after each "gross" calculation that the output remained so, but that only reduced the number of bad residuals by 3 out of 4118 total input points.) So, I’m wondering if there’s either a "convenient" way to simulate single-precision arithmetic in Matlab (I searched File Exchange for relevant functions, but found none) or to estimate/bound the "error" introduced by using single-precision arithmetic (including power/root and exponential/log functions) instead of double. Thanks! Hi! I’m trying to replicate, in Matlab, compiled algorithms implemented in C using single-precision arithmetic; I have the C source code, and an executable which is reputed to implement said C source, but no convenient means to compile and link said source myself. (Yes, I know I can download the Microsoft C compiler, incl. a no-frills version of Visual Studio, for free, but that’s hardly "convenient.") I’ve implemented the algorithms and I’m 99% sure they’re right because the "residuals" (the difference between my results and those of the original C implementations) are more-or-less randomly distributed around zero, and about 85% of them are within half of the precision of the C implementations’ output (which varies, but, for example, when it’s 1e-4, 85% of my residuals satisfy abs(res)<5e-5). It’s the other 15% that leave me 1% uncertain, and my attempts to explain the discrepancy have brought me to the single/double precision issue: I have good cause to suspect that the C implementations are using single-precision arithmetic, and I’ve been led to believe that Matlab always performs double-precision arithmetic, even on single precision "data," yes? (I tried making ‘single’ all the data in my implementation, and confirmed after each "gross" calculation that the output remained so, but that only reduced the number of bad residuals by 3 out of 4118 total input points.) So, I’m wondering if there’s either a "convenient" way to simulate single-precision arithmetic in Matlab (I searched File Exchange for relevant functions, but found none) or to estimate/bound the "error" introduced by using single-precision arithmetic (including power/root and exponential/log functions) instead of double. Thanks! single precision arithmetic, estimating error MATLAB Answers — New Questions

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